Flat sample bags are to be understood as, e.g., bags which consist of two pieces of a film material welded together on all sides or of one folded such piece welded together on three sides, Such sample bags are usually filled with liquid, pasty or powdery contents or contain solid, more or less flat objects. This kind of sample bag is mostly produced from two quasi-endless webs of film-type material wherein the webs are guided against each other and are welded together along their longitudinal edges. At the same time, the webs are welded together transversely at regular intervals and the bags thus produced are filled between the steps of transverse welding. It is also possible for only one web of film-type material to be used, the web being folded parallel with its longitudinal edges and the two longitudinal edges are welded to form a welded edge opposite the folded edge. In both cases, a web of sample bags is formed which is then separated into individual sample bags.
Flat sample bags of the kind described above are often further processed by supplying them into the continuous processing of other objects to be added to the latter in any manner. For example, the sample bags may be laid or glued into printed products or they may be added to the packing of other objects or introduced into envelopes together with printed matter.
For the automatic feeding of the described sample bags into further processing with a high throughput, the sample bags are, e.g., filled into suitable boxes in which they are arranged in the form of a horizontal stack. In publication EP-0 706 967 (or U.S. Pat. No. 5 601 396), a method for handling sample bags ordered in this manner is described. However, it shows that further measures are necessary if feeding speeds of 40,000 to 60,000 bags per hour are to be achieved, i.e., speeds which are, e.g., usual in the processing of printed products into which sample bags are to be glued.
Such further measures are proposed in the publication EP-739 822. These measures are based on the finding that the problems occurring when handling the bags at high speed are caused by the fact that the bags do not have a stable form and thus are difficult to grip. In the above publication, it is suggested that the form of the bags be changed such that it is more precisely defined and such that the bags can be stacked more easily.
It is also known not to separate the sample bags from each other and to feed them into further processing in the form of a web of sample bags. For this purpose, discrete lengths of a web of sample bags are rolled up to form, e.g., rolls which are positioned on suitable unwinding devices for feeding. It is known also to produce and feed the web of sample bags quasi on-line by transporting the web to the feeding location in hanging loops and, if necessary, buffering the web in this form between production and further processing. In these methods, the bags do not need to be gripped individually and therefore high feeding performances can be achieved. This advantage, however, must be paid for with considerable additional cost for additional apparatus. Methods for feeding webs of sample bags are, e.g., described in the publications EP-0 292 891 (or U.S. Pat. No. 4 901 935) and EP-0 253 959 (or U.S. Pat. No. 4 841 714).